Comments on: Website Speed Optimization and Waterfall Diagram

By: compound bows

compound bows — Thu, 03 Dec 2009 11:47:50 +0000

Using parallel images using host names is not always reliable. However, I agree with your point of view to some extent.

By: Patrick Meenan

Patrick Meenan — Mon, 23 Mar 2009 18:57:37 +0000

The online version of pagetest that was used in the article runs the tests through a real IE browser at one of the hosted locations (Virginia and New Zealand) so you’re not reliant on the developer’s connection (which is often very fast and has low latency to the servers). That’s actually the main reason I bothered even putting up the site because I couldn’t find any (free) tools that weren’t running simulated browsers.

aol.com was re-launched recently which probably accounts for the difference in count but it didn’t get any lighter – it’s now at around 130 requests . The only other hosted tool I’m aware of that uses a real browser is Keynote. They also have some free testing that you can run tests from 5 different locations around the world (though at backbone speeds which tend to differ enough from end-user connections that you want to look at both).

By: zuborg

zuborg — Thu, 11 Dec 2008 19:31:13 +0000

2Patrick: Btw, yahoo.com looks at User-Agent header, for unknown UAs it shows special simple page with little number of images. For http://www.aol.com Site-Perf.com fetch 53 objects.

You are right that only browser is able to show what happens there when browser do some work, thus FireBug Firefox addon is irreplaceable for webdevelopers. The only problem is that FireBug and similar tools relies on internet link of those who use it

By: Patrick Meenan

Patrick Meenan — Sat, 29 Nov 2008 13:49:13 +0000

Site-Perf looks interesting but the browser “emulation” apprears to be pretty lacking. Testing http://www.aol.com only requests the base page (there are actually over 100 requests for the page) and http://www.yahoo.com only requests the base page and 4 images (also supposed to be a lot larger).

There really is no substitute for using a real browser. Even the best emulators I have seen (from companies that sell the service) don’t quite get it right.

If there’s something you’d like to see in the online version of pagetest just shoot me a note and I’ll see what I can do (there is a contact me link on the site).

By: Nail

Nail — Sat, 29 Nov 2008 13:13:24 +0000

zuborg,
IE7 is still most popular browser and it makes only 2 connections per host. According to http://stevesouders.com/ua/ in IE8 it will be 6 connections per host which is definitely will help performance.
Though page compositions will be still actual since pages usually have much more components and because of HTTP request cost.
About Site-Perf.com, it’s a very good tool, also it would be good to have some presets for Link control, something like GPRS connection, Europe ADSL, etc.

By: Nail

Nail — Sat, 29 Nov 2008 13:11:25 +0000

frederic,
Thanks for the addition, sure there are more things like server-side gzip compression, CDN, etc.
In this post I wanted to describe page composition issues and how to use tools to look how browsers load pages and how to measure performance from end-user point of view.

By: zuborg

zuborg — Wed, 19 Nov 2008 15:54:42 +0000

Nice article

But nowadays is more common limit 6-8 connections per host, IE8 will have 8 too (as far as I know).

http://performance.webpagetest.org:8080/ is nice tool too, but I would also recommend to try this one speedmeter – http://Site-Perf.com/
It’s highly customizable, supports a lot of features like Keep-Alive, HTTP-Compression and HTTP-Auth…
Also there is tool to measure packetloss level on internet link of you server.

By: frederic sidler

frederic sidler — Tue, 11 Nov 2008 21:32:30 +0000

firebug with yslow and the 10 yahoo rules is also worth reading.

you can also use yuicompressor to concatenate JS and CSS

you can gzip these files too (make sure you have zip and non-zip version in case the client browser does not support it)

You denfinitely should use a version number in your JS and CSS files and set the cache never to expire so that you will never retrieve these files again if they have not changed.

Last, you can use a CDN to host these files so that your server will never be hit.

By: Nail

Nail — Tue, 11 Nov 2008 00:09:18 +0000

John,
Yes, for this case we could use several hostnames to load images in parallel.
It’s not always applicable though, I mean there are sites with 50+ images and we are limited with DNS requests – they can slow down page loading. Plus browser will have to establish 2 connection per hostname.

By: John Laur

John Laur — Mon, 10 Nov 2008 18:03:23 +0000

Instead of CSS Sprites (which I personally despise) you could host images (and CSS/JS for that matter) on separate hostnames but the same webserver (via CNAMEs) to improve download concurrency. It’s not a particularly good technique if you use heavy apache processes to serve both your dynamic and static content, but paired with a lightweight frontend server (ngnix, lighttpd, pound) it will help tremendously without having to jack around with page layout and the horrible junk that is CSS sprites.